Feature/vcloudng

Hi there!

This is a complete new implementation of vCloud director 1.5 from the ground up, i've called it **vcloudng** to avoid conflits with the current vcloud provider. It has great new features, like lazy load of collections to dramatically improve the performance. It handles vcloud tasks seamless so you don't have to worry about it. In addition of request, parsers and models, i've added a new layer called generators, which it takes care of generating a valid xml document from a ruby data structure. You can check out all the features and usage in the `documentation.md` file

My motivation to develop it came after using the current implementation of vcloud provider for a month, it fails erratically, models are broken so i had to use the requests directly, witch it made it quite cumbersome. It didn't make sense to write a layer on top of that to workaround the lack of consistency and error handling. Fixing it wasn't an option since i'd have to change the API to make it consistent.

I haven't implemented any testing yet since i'm on a tight schedule, but i'm planning to make it in the following months.

Nework firewalling isn't implemented yet but i'll implement it in late August

Hope this new vcloud provider makes the life of people working with vmware vCloud Director technology easier.

Thanks,

Rodrigo Estebanez